Stage 3 of Sleep

The third stage of sleep is stage 3, which can also be called Delta Sleep. Sometimes, it is hard to differentiate between stages 3 and 4, but there is a trick - Stage 3 is known to have less than 50% of delta waves, while stage 4 has more than 50%.
Delta waves are the slowest, with the highest amplitude, brain waves. Stage 3 is known to have both delta waves, combined with occasional faster waves. Below is a picture of what the brain waves look like during stage 3 of sleep:
untitled.jpg(Hall, 1998)

During Stage 3

An interesting fact about stage 3 sleep is that it is the deepest sleep a person experiences. With that being said, it is the most difficult stage to wake a person up during. When a person is finally awoken during stage 3 of sleep, they may feel a bit groggy and disoriented for a few minutes. (Stibich, 2008)
Another interesting note is that it is during Stage 3 (and 4) that sleep-talking and sleep-walking will most likely occur. (Hall, 1998)

Resources

Hall, Richard (1998). Psychology World. Stages of Sleep. Retrieved on January 4, 2009, from http://web.mst.edu/~psyworld/sleep_stages.htm.
Stibich, Mark, Ph. D. (2008). About.com. The Stages of Sleep. Retrieved on January 4, 2009, from http://longevity.about.com/od/sleep/a/sleep_stages.htm.


Julie Kuberski
AP Psychology
Robillard
January 4, 2009